The word(s) "once" appears 85 time(s) in 79 verse(s) in Quran in Muhammad Habib Shakir translation.

(41) So she conceived him; then withdrew herself with him to a remote place.

(42) So Musa conceived in his mind a fear.

(43) He cannot be questioned concerning what He does and they shall be questioned.

(44) And Dawood and Sulaiman when they gave judgment concerning the field when the people's sheep pastured therein by night, and We were bearers of witness to their judgment.

(45) And those who disbelieve shall not cease to be in doubt concerning it until the hour overtakes them suddenly, or there comes on them the chastisement of a destructive day.

(46) Do not hold the Apostle's calling (you) among you to be like your calling one to the other; Allah indeed knows those who steal away from among you, concealing themselves; therefore let those beware who go against his order lest a trial afflict them or there befall them a painful chastisement.

(47) And those who disbelieve say: Why has not the Quran been revealed to him all at once? Thus, that We may strengthen your heart by it and We have arranged it well in arranging.

(48) But if we could but once return, we would be of the believers.

(49) And most surely your Lord knows what their breasts conceal and what they manifest.

(50) And there is nothing concealed in the heaven and the earth but it is in a clear book.